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<p>Nickel chromite (NiCr<sub>2</sub>O<sub>4</sub>) was synthesized via the co-precipitation method and characterized for its physical and photoelectrochemical properties. Thermal gravimetry (TGA) and X-ray diffraction (XRD) analyses confirmed the formation of a single-phase cubic structure (space group: Fd-3&#xa0;m) at temperatures above 850&#xa0;°C. Transmission electron microscopy (TEM) revealed crystallite agglomeration, while diffuse reflectance spectroscopy indicated a direct optical transition with a bandgap energy of 1.76&#xa0;eV. The material exhibited p-type behavior, with a flat band potential (E<sub>fb</sub>) of 0.57&#xa0;V vs. SCE, determined from capacitance-potential measurements. To enhance photocatalytic activity, a novel visible-light-responsive NiCr<sub>2</sub>O<sub>4</sub>/TiO<sub>2</sub> heterojunction was synthesized and evaluated for the degradation of malachite green (10&#xa0;mg/L) at neutral pH. Individually, TiO<sub>2</sub> and NiCr<sub>2</sub>O<sub>4</sub> achieved degradation rates of 42% and 58% after 180&#xa0;min. However, the 50&#xa0;wt %–50&#xa0;wt % p-n NiCr<sub>2</sub>O<sub>4</sub>/TiO<sub>2</sub> heterojunction significantly improved performance, achieving a 90% degradation rate. This enhancement is attributed to improved charge separation and reduced electron–hole recombination, facilitating the generation of reactive species. Scavenger experiments with EDTA-2Na and ascorbic acid revealed that holes (h⁺) and superoxide radicals (O<sub>2</sub><sup>•−</sup>) play a key role in the photocatalytic process.</p>

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Enhanced photocatalytic degradation of malachite green dye by NiCr2O4/TiO2 heterojunction under solar irradiation

  • 期刊论文

  • 发表日期：

    2025年3月28日

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  • Dina Chaibeddra,
  • Messaoud Benamira,
  • Mohamed Hamdi,
  • Yassine Azoudj,
  • Hajir Wahbi,
  • Ivalina Avramova

摘要

Nickel chromite (NiCr2O4) was synthesized via the co-precipitation method and characterized for its physical and photoelectrochemical properties. Thermal gravimetry (TGA) and X-ray diffraction (XRD) analyses confirmed the formation of a single-phase cubic structure (space group: Fd-3 m) at temperatures above 850 °C. Transmission electron microscopy (TEM) revealed crystallite agglomeration, while diffuse reflectance spectroscopy indicated a direct optical transition with a bandgap energy of 1.76 eV. The material exhibited p-type behavior, with a flat band potential (Efb) of 0.57 V vs. SCE, determined from capacitance-potential measurements. To enhance photocatalytic activity, a novel visible-light-responsive NiCr2O4/TiO2 heterojunction was synthesized and evaluated for the degradation of malachite green (10 mg/L) at neutral pH. Individually, TiO2 and NiCr2O4 achieved degradation rates of 42% and 58% after 180 min. However, the 50 wt %–50 wt % p-n NiCr2O4/TiO2 heterojunction significantly improved performance, achieving a 90% degradation rate. This enhancement is attributed to improved charge separation and reduced electron–hole recombination, facilitating the generation of reactive species. Scavenger experiments with EDTA-2Na and ascorbic acid revealed that holes (h⁺) and superoxide radicals (O2•−) play a key role in the photocatalytic process.